LIVE POLIO IRUS VACCINES

338 Efficacy--Laboratory Evidence
GROUP:
TABLE 4.
POLIO ANTIBODY STATUS AND SALK HISTORY
922 LEDERLE EMPLOYEES & FAMILIES
DOSE: NONE TO FOUR SALK SHOTS DATE: 1959-60
NEGATIVE TOTAL I PERSONS WITH SALK SHOTS
TO TYPE PERSONS NONE 1 OR 2 3 OR 4
No. % I No. % No. % No. %
0 441 47.8 269 41.1 61 53.5 111 72.0
1 100 10.8 76 11.6 14 12.3 10 6.5
3 129 13.9 90 13.7 19 16.7 20 12.9
1 & 3 53 5.7 i 34 5.2 8 7.0 11 7.1
2 58 6.3 52 7.9 4 3.5 2 1.3
1 & 2 45 4.9 45 6.9 0 0 0 0
2 & 3 37 4.0 36 5.5 1 .9 0 0
1, 2 & 3 59 6.4 52 7.9 7 6.1 0 0
TOTALS 1922 654 114 154
TABLE 5. FREQUENCY OF SERONEGATIVES IN
SALK-VACCINATES AND NON-VACCINATES
NO. OF
PERSONS
654
114
154
NO. OF SERONEGATIVES (%)
SALK SHOTS
TO TYPE
1 2 3
O 31.7 28.3 32.4
1-2 25.4 10.5 30.7
3+ 13.6 1.3 20.1
cent for Types 1 and 2 and 97 per cent for Type
3. Moreover, from 37 to 45 per cent of those who
had pre-vaccination antibody titers in the range
of 1:4 to 1:512 showed four-fold or greater booster
responses.
DISCUSSION
The data summarized in the present report are
essentially an extension of our earlier study of
trivalent vaccine which began in May 1958 with
the simultaneous feeding of three capsules, each
containing one of the three poliovirus strains.2
This initial test was followed by the feeding of a
fluid vaccine that contained balanced amounts of
each of the three types of virus.l The results of
those efforts were such as to justify the hope that
the oral vaccination procedure could be simplified
and made more rapid and less expensive,
without any appreciable sacrifice of either efficiency
or safety. Results obtained since in more
than 1,200 additional volunteers confirm the
earlier findings and provide a substantial basis
for the greatly expanded field trials that are now
in progress.
The 88 per cent over-all conversion rate of
seronegatives to seropositives, obtained in the
present trivalent oral vaccine study, is comparable
to, or slightly better than, rates reported
for the separate feeding of the same strains of
virus in children in Minnesota (85 per cent),3
Colombia (83 per cent),' and Cuba (85 per
cent).2 It is noteworthy, too, that for the most
part, these conversions are based on sera collected
four to five weeks after a single feeding. The
conversion rates for virus Types 1 and 3, epidemiologically
the most important, were over 93